Although child mental health problems are among the most important worldwide issues, development of culturally acceptable mental health services to serve the clinical needs of children and their families is especially lacking in regions outside Europe and North America.
Trang 1R E S E A R C H Open Access
Normative data and psychometric properties of the strengths and difficulties questionnaire
among Japanese school-aged children
Aiko Moriwaki and Yoko Kamio*
Abstract
Background: Although child mental health problems are among the most important worldwide issues,
development of culturally acceptable mental health services to serve the clinical needs of children and their families
is especially lacking in regions outside Europe and North America The Strengths and Difficulties Questionnaire (SDQ), which was developed in the United Kingdom and is now one of the most widely used measurement tools for screening child psychiatric symptoms, has been translated into Japanese, but culturally calibrated norms for Japanese schoolchildren have yet to be established To this end, we examined the applicability of the Japanese versions of the parent and teacher SDQs by establishing norms and extending validation of its psychometric properties to a large nationwide sample, as well as to a smaller clinical sample
Methods: The Japanese versions of the SDQ were completed by parents and teachers of schoolchildren aged 7 to
15 years attending mainstream classes in primary or secondary schools in Japan Data were analyzed to describe the population distribution and gender/age effects by informant, cut-off scores according to banding, factor structure, cross-scale correlations, and internal consistency for 24,519 parent ratings and 7,977 teacher ratings from a large nationwide sample Inter-rater and test-retest reliabilities and convergent and divergent validities were confirmed for a smaller validation sample (total n = 128) consisting of a clinical sample with any mental disorder and community children without any diagnoses
Results: Means, standard deviations, and banding of normative data for this Japanese child population were obtained Gender/age effects were significant for both parent and teacher ratings The original five-factor structure was replicated, and strong cross-scale correlations and internal reliability were shown across all SDQ subscales for this population Inter-rater agreement was satisfactory, test-retest reliability was excellent, and convergent and divergent validities were satisfactory for the validation sample, with some differences between informants
Conclusions: This study provides evidence that the Japanese version of the SDQ is a useful instrument for parents and teachers as well as for research purposes Our findings also emphasize the importance of establishing culturally
calibrated norms and boundaries for the instrument’s use
Keywords: Child mental health, Questionnaire, Reliability, Validity, Normative banding, Strengths and difficulties
questionnaire
* Correspondence: kamio@ncnp.go.jp
Department of Child and Adolescent Mental Health, National Institute of
Mental Health, National Center of Neurology and Psychiatry, 4-1-1
Ogawa-Higashi, Kodaira, Tokyo 187-8553, Japan
© 2014 Moriwaki and Kamio; licensee BioMed Central Ltd This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use,
Trang 2Mental health problems affect 10-20% of children and
adolescents worldwide [1], and substantial evidence
indi-cates continuity in psychopathology from childhood into
adulthood [2-4] Despite heightened public concern in
Japan for childhood mental health problems [5-7], many
of these children remain unidentified and have no access
to professional support due to various barriers including
an insufficient specialized community health service
sys-tem and parents or school teachers having inadequate
knowledge of and stigma against child mental health
problems Recognizing this urgency, the Japanese
Minis-try of Health, Labour and Welfare has provided basic
training opportunities for primary health professionals
and promoted multidisciplinary work in the community
since 2008 In addition, in 2009, the Ministry of Education,
Culture, Sports, Science and Technology revised the
School Health Act to strengthen the role that school
personnel play in the early identification of children with
mental health problems
To support such initiatives, we need to develop
reli-able and valid measurement tools of psychopathological
symptoms in Japanese children At present, among the
various questionnaires available for measuring mental
health problems in children and adolescents, the Child
Behavioral Checklist (CBCL) [8] has long been viewed as
the“gold standard” because of its comprehensive nature
Although the CBCL is a solid instrument for conducting
in-depth assessment, the 25-item Strengths and
Difficul-ties Questionnaire (SDQ) [9] may be more suitable for
screening purposes The SDQ was created by Goodman
by adding items on concentration, peer relations, and
so-cial competence to the established Rutter questionnaires
Because the SDQ measures not only behavioral
prob-lems but also the strengths of children and adolescents
aged 4–16 years [10], parents and teachers can easily
complete it Furthermore, authorized translations of the
SDQ are available free of charge [11]; http://www
sdqinfo.com Due to its ease of use, the SDQ has now
been translated into more than 75 languages and
exten-sively validated in clinical and community samples
[12-25] These prior studies revealed that
population-specific SDQ norms vary widely across countries
To the best of our knowledge, only one study has
ex-amined the Japanese version of the SDQ That study
an-alyzed parent ratings in a community sample of 2,899
children aged 4–12 years [18] and found a gender effect
on parent ratings, showed cut-off scores according to
score banding, and confirmed its five-factor structure
and satisfactory internal consistencies However, given
the value of having multiple informants reporting on
children’s mental health problems especially for
psycho-logical assessment [26,27], we must examine whether its
psychometric properties differ by rater Also, to evaluate
clinical usefulness, we need to examine it in a psychiatric clinical population as well as in a community popula-tion The urgency to enhance school mental health care necessitates establishing culturally calibrated norms for Japanese schoolchildren based on a nationwide sample rather than on data from a restricted local area Therefore, this study examined the applicability of the Japanese ver-sion of the SDQs for parents and teachers by establishing norms and cut-offs according to bandings and extending validation of its psychometric properties to a large, nation-wide, and representative sample as well as a smaller clin-ical sample
Methods This cross-sectional epidemiological study investigated the score distribution with gender and age effects, factor structure, reliability, and validity of the Japanese versions
of the parent and teacher SDQs
Participants and data collection Participants comprised a large-sized sample recruited from primary and secondary schools (normative sample) and a small-sized sample (validation sample) that was lo-cally recruited The schools were recruited countrywide with assistance from the Japanese Ministry of Education, Culture, Sports, Science, Technology and local govern-ment boards of education We did not include private schools, national schools, or schools for handicapped children Data were collected between December 2009 and March 2010 at the end of the Japanese school year
to ensure that teachers knew their students well
Normative sample The parent SDQ to be completed at home was distrib-uted to all parents of schoolchildren (aged 7–15 years) attending mainstream classes in 148 primary schools and 71 secondary schools in the 10 geographical areas making up Japan, with a letter from the investigators and school principals informing them about the study From the parents of 87,548 children, 25,779 returned questionnaires to the investigators (29.4% response rate) Among these schools, 142 primary schools and 69 sec-ondary schools (2,769 classes) agreed to participate in the teacher rating portion of the study First, parents were informed about the study with a letter from the in-vestigators and school principals Second, among school-children whose parents gave written consent, classroom teachers chose 4 children (2 boys, 2 girls) per class using
a predetermined rule In classes where less than 4 par-ents gave consent, teachers were asked to complete the questionnaire for all children whose parents who con-sented We received 8,272 questionnaires rated by 2,183 teachers (78.8% response rate; 2,183/2,769) Among all questionnaires returned, we excluded 1,260 parent
Trang 3ratings (4.9%) and 295 teacher ratings (3.6%) with one or
more missing answers, leaving 24,519 parent ratings
(12,472 boys, 12,047 girls) and 7,977 teacher ratings
(4,010 boys, 3,967 girls) Each of 9 grade levels
com-prised a minimum of 815 parent ratings and 302 teacher
ratings for each gender (Table 1) The parent SDQ was
rated by mothers (91.1%), fathers (7.6%), both parents
(0.7%), and others (0.6%) The ratio of raters did not
dif-fer significantly between boys and girls (χ2
= 1.27,ns) or
by age (χ2
= 2.11, ns) Therefore, the parent SDQ data
rated by different raters were combined and analyzed in
subsequent analyses
Validation sample
Participants were recruited from research volunteers
with or without mental disorders, local schools, or a
local pediatric outpatient clinic specializing in
neurode-velopmental disorders Participants totaled 128 children
aged 6 to 16 years, of which 73 had any psychiatric
diag-nosis and 55 had no diagdiag-nosis (19 typically developing,
29 from community schools) Psychiatric diagnoses given
by child psychiatrists or developmental pediatricians
were autism spectrum disorder (n = 47),
attention-deficit/hyperactivity disorder (n = 23), anxiety disorder
(n = 2), specific phobia (n = 14), social phobia (n = 4),
obsessive-compulsive disorder (n = 1), adjustment
dis-order (n = 2), tic disdis-orders (n = 5), and others (n = 7)
Thirteen of 73 children with any mental disorder had
more than one diagnosis Parent ratings were obtained
for 108 children (69 clinical), and teacher ratings were
obtained for 75 children (42 clinical) To examine
inter-rater reliability, we used data from 63 participants rated
by both parent and teacher at almost the same time
We collected retest data from the parents of 34
chil-dren 14 to 137 days later, and teachers of 18 chilchil-dren
10 to 107 days later (practical limitations precluded a shorter collection interval)
Measures Strengths and difficulties questionnaire The SDQ is a 25-item questionnaire assessing child psychopathology and positive strengths of children and adolescents Twenty-five items are classified into five subscales, four difficulties subscales (emotional symptoms, conduct problems, hyperactivity/inattention, peer prob-lems) and one subscale on prosocial behavior Each item
is scored on a 3-point scale (0 = not true, 1 = somewhat true, 2 = certainly true) Each subscale score ranges from 0
to 10, and four difficulties subscale scores add up to a total difficulties score (range 0–40); higher difficulties scores in-dicate more difficulties, whereas the prosocial subscale score is reversely coded The authorized Japanese transla-tions of the SDQ [28] were used in this study
Child behavioral checklist The CBCL, a 113-item questionnaire assessing child psy-chopathology, comprises eight subscales (withdrawal problems, somatic complaints, anxious/depressed, social problems, thought problems, attention problems, delin-quent behavior, aggressive behavior) [8] After each item
is scored on a 3-point scale, eight individual subscale scores, an internalizing score (withdrawal problems, somatic complaints, and anxious/depressed subscales),
an externalizing score (delinquent and aggressive behav-ior subscales), and a total score can be calculated The Japanese version was shown to be valid and reliable [29,30] and to have an 8-syndrome structure [31] In this study, 46 parents and 29 teachers of primary schoolchil-dren in the validation sample completed the CBCL for Ages 4–18 (CBCL/4-18) and the Teacher Rating Form (TRF), respectively
ADHD-rating scale-IV The ADHD-Rating Scale-IV (ADHD-RS) is an 18-item questionnaire assessing symptom frequency characterized
by attention deficit/hyperactivity disorder in children and adolescents [32] Each item is scored on a 4-point scale, and inattention (sum of odd-numbered items), hyperactivity-impulsivity (sum of even-numbered items), and total score (sum of all items) can be calculated The Japanese versions of the ADHD-RS home and school forms were shown to be valid, reliable, and to have a two-factor structure [33,34] In this study, 41 parents and 43 teachers of primary schoolchildren completed the home form and school form, respectively
Ethical considerations The study protocol was approved by the Ethics Committee
of the National Center of Neurology and Psychiatry, Japan,
Table 1 Number of children in the normative sample by
gender and grade
Grade SDQ parent ratings
(n = 24,519)
SDQ teacher ratings (n = 7,977)
1 1,792 14.4 1,633 13.6 526 13.1 519 13.1
2 1,662 13.3 1,514 12.6 547 13.6 540 13.6
3 1,526 12.2 1,541 12.8 481 12.0 485 12.2
4 1,479 11.9 1,506 12.5 509 12.7 506 12.8
5 1,562 12.5 1,382 11.5 499 12.4 478 12.0
6 1,321 10.6 1,334 11.1 484 12.1 486 12.3
7 1,162 9.3 1,186 9.8 346 8.6 343 8.6
8 1,100 8.8 1,136 9.4 316 7.9 307 7.7
Note SDQ, strengths and difficulties questionnaire Most grade 1 participants
were 7 years old at the time of the survey.
Trang 4and was performed in accordance with the ethical
stan-dards laid down in the 1964 Declaration of Helsinki and its
later amendments We obtained written informed consent
to participate in this study from the caregivers of each child
participant
Statistical analysis
Because the SDQ score distribution in the normative
sample was significantly different from a normal
distri-bution (Shapiro-Wilk and Kolmogorov-Smirnov tests,
both p < 01), subsequent statistical analyses employed
non-parametric tests To examine gender effects, we
used the Mann–Whitney U-test to compare scale scores
between boys and girls To examine age effects, we used
the Kruskal-Wallis test and post-hoc Mann-Whitney’s
comparisons with Bonferroni correction on the scale
scores of three age groups (7–9, 10–12, 13–15 years)
We conducted exploratory factor analysis (EFA) with
varimax rotation and confirmatory factor analysis (CFA)
on the normative sample to confirm the five-factor
model On the normative sample, we calculated internal
consistency for the total difficulties score and each
sub-scale score, and we assessed cross-sub-scale correlations
be-tween the five scales using Spearman’s rank correlations
Inter-rater and test-retest reliabilities and convergent
and divergent validities were assessed using Spearman’s
rank correlations on the validation sample We also
ex-amined temporal stability using a repeated-measures
Wilcoxon signed-rank test on scores rated on two
occa-sions for a smaller validation sample All statistical
analysis was performed with SPSS version 17.0 and AMOS version 10.0
Results Population distribution, and gender and age effects Table 2 shows the means and standard deviations of parent- and teacher-rated SDQ scores in the normative sample, and also gender and age effects on the SDQ scores Gender effects were significant for both parent and teacher ratings on total difficulties and all five sub-scale scores (total difficulties: U = 67,710,000, 5,796,000; emotional symptoms:U = 70,330,000, 7,782,000; conduct problems: U = 69,980,000, 6,558,000; hyperactivity/in-attention: U = 61,150,000, 5,180,000; peer problems: U = 73,270,000, 7,140,000; prosocial behavior: U = 67,710,000, 5,796,000 [for parent and teacher ratings, respectively,
p < 0.001 for all except teacher-rated emotional symp-toms, p < 0.05 for teacher-rated emotional symptoms]) Parent ratings showed that boys scored significantly higher than girls on total difficulties and on the con-duct problems, hyperactivity/inattention, and peer problems subscales, whereas girls scored significantly higher than boys on the emotional symptoms and pro-social behavior subscales However, the effect sizes (r)
of these gender differences were negligible Teacher rat-ings, on the other hand, showed that boys scored sig-nificantly higher than girls on total difficulties and on all of the difficulties subscales, whereas girls scored significantly higher than boys on the prosocial behav-ior subscale The effect sizes (r) of gender differences
Table 2 Mean scores of parent- and teacher-rated SDQs and gender and age effects
(p, r)
7-9 years 10-12 years 13-15 years Age effect
(p, Cramer ’s V)
Parent ratings (n = 12,472) (n = 12,047) (n = 9,968) (n = 8,584) (n = 6,267)
Total difficulties 8.02 (5.26) 7.11 (4.76) ‡ 8.39 (5.09) 7.20 (4.94) 6.82 (4.94) a‡ b‡ c‡, 0.15 Emotional symptoms 1.31 (1.67) 1.49 (1.76) ‡ 1.59 (1.77) 1.33 (1.67) 1.21 (1.68) a‡ b‡ c‡, 0.11 Conduct problems 1.92 (1.59) 1.70 (1.43) ‡ 2.01 (1.57) 1.74 (1.50) 1.62 (1.43) a‡ b‡ c‡, 0.12 Hyperactivity/inattention 3.23 (2.30) 2.49 (1.98) ‡ 3.27 (2.26) 2.69 (2.13) 2.49 (2.00) a‡ b‡ c‡, 0.16 Peer problems 1.55 (1.69) 1.42 (1.50) ‡ 1.52 (1.57) 1.44 (1.58) 1.51 (1.68) a‡
Prosocial behavior 5.80 (2.15) 6.50 (2.08) ‡ 6.18 (2.10) 6.26 (2.15) 5.91 (2.20) a† b‡ c‡ Teacher ratings (n = 4,010) (n = 3,967) (n = 3,098) (n = 2,962) (n = 1,917)
Total difficulties 6.37 (5.80) 3.95 (4.50) ‡, 0.24 5.74 (5.70) 4.94 (5.22) 4.58 (4.79) a‡ c‡
Emotional symptoms 0.82 (1.48) 0.77 (1.42) † 0.93 (1.55) 0.76 (1.44) 0.64 (1.23) a‡ b‡ c† Conduct problems 1.20 (1.68) 0.68 (1.22) ‡ 1.06 (1.61) 0.90 (1.45) 0.81 (1.35) a† c‡
Hyperactivity/inattention 2.89 (2.67) 1.37 (1.76) ‡, 0.31 2.46 (2.60) 2.01 (2.32) 1.79 (2.04) a‡ c‡
Peer problems 1.47 (1.86) 1.13 (1.56) ‡ 1.30 (1.71) 1.28 (1.75) 1.34 (1.73)
Prosocial behavior 5.73 (2.74) 7.14 (2.49) ‡, 0.26 6.47 (2.68) 6.48 (2.70) 6.28 (2.76) c†
Note SDQ, strengths and difficulties questionnaire Age bands 7–9 years, 10–12 years, 13–15 years correspond to grades 1–3, 4–6, 7–9, respectively.
Age effect:a7–9 yrs > 10–12 yrs, b
10–12 yrs > 13–15 yrs, c
7–9 yrs > 13–15 yrs † p < 0.05,‡p < 0.001.
Trang 5hyperactivity/inattention and prosocial behavior
sub-scale scores were small (0.24-0.31), although the rest
were negligible (Table 2)
Age effects were also significant for both parent and
teacher ratings except for the teacher-rated peer
prob-lem subscale As for parent ratings, total difficulties and
all subscale scores were significantly different by age
band (total difficulties:χ2
= 568.33; emotional symptoms:
χ2
= 307.30; conduct problems: χ2
= 323.96; hyperactiv-ity/inattention: χ2
= 586.60; peer problems: χ2
= 19.26;
prosocial behavior:χ2
= 88.62 [all p < 0.001]) Differences
by age band were similar but diminished for teacher
rat-ings (total difficulties: χ2
= 51.75; emotional symptoms:
χ2
= 59.14; conduct problems: χ2
= 18.69; hyperactivity/
inattention: χ2
= 71.61, all p < 0.001; peer problems: χ2
= 5.64, ns; prosocial behavior:χ2
= 6.77,p < 0.05) Post hoc comparisons between three age bands indicated that
SDQ scores tended to be higher in younger children, as
shown in Table 2 The effect size (Cramer’s V) of age
ef-fects was small for parent-rated total difficulties,
emo-tional symptoms, conduct problems, and hyperactivity/
inattention subscale scores, although negligible for all
teacher-rated scores
Normative banding and cut-off score
Because gender or age effects were consistently observed
for the total difficulties scores (Table 2), score ranges of
the three bands (clinical, borderline, normal) were
deter-mined for the total difficulties scores by gender and age
group (7–9, 10–12, 13–15 years) (Table 3) According to
Goodman’s original work [10], the highest 10th
percent-ile of the normative sample is defined as the “clinical”
range, the next 10th percentile as the“borderline” range,
and the remaining 80th percentile as the“normal” range
Although discrete scores made it impossible to divide
the sample into exact percentiles, as Table 3 shows,
nearly 10%, 10%, and 80% of the children were in the
clinical, borderline, and normal bands
Factor analysis Table 4 shows rotated factor loadings for a five-factor EFA performed on parent- and teacher-rated SDQ scores with a rearranged item order Only five factors had eigenvalues greater than 1.00, consistent with the original study [14] and the previous Japanese study [18] EFA revealed that the five factors accounted for 33.03% and 55.22% of total variance of parent and teacher rat-ings, respectively, and most items loaded moderately to strongly onto their predicted factors Communality values for teacher ratings were generally fair, at over 0.40 for 23 of 25 items, whereas only 7 of 25 items exceeded 0.40 for parent ratings Parent- and teacher-rated item 7 (“obedient”) and teacher-rated item 14 (“popular”) loaded onto the prosocial factor more strongly than onto the predicted factor The loading of parent-rated item 10 (“fidgety”) onto the emotional factor was also higher than that onto the predicted factor
Furthermore, CFA results lend support to the five-factor structure of the SDQ; for the parent and teacher ratings, respectively, the comparative fit index was 0.83 and 0.86, the goodness of fit index was 0.93 and 0.89, the adjusted goodness of fit index was 0.91 and 0.86, and the root mean square error of approximation was 0.06 and 0.07 In addition, the 3 items (7, 10, 14) mentioned above were found to load onto the predicted factor with factor loadings >0.40 (0.43-0.75)
Cross-scale correlations Table 5 presents cross-scale correlations among five subscales by rater and gender Correlations between externalizing-externalizing scales, that is, between con-duct problems and hyperactivity/inattention, were strong (parent ρ = 0.48, teacher ρ = 0.53) By contrast, those between internalizing-externalizing scales were small (between emotional symptoms and conduct prob-lems: parent ρ = 0.28, teacher ρ = 0.25; between emo-tional symptoms and hyperactivity/inattention: parent
ρ = 0.28, teacher ρ = 0.32) Prosocial behavior was
Table 3 Normative banding of total difficulties score for parent- and teacher-rated SDQs for Japanese children
Raw score (%) Raw score (%) Raw score (%) Raw score (%) Raw score (%) Raw score (%) Parent rating Normal 0-13 82.0% 0-11 81.0% 0-11 79.8% 0-10 82.0% 0-10 79.7% 0-10 81.5%
Borderline 14-16 9.0% 12-14 9.7% 12-14 9.9% 11-13 8.2% 11-14 11.3% 11-13 8.9% Clinical 17-40 9.0% 15-40 9.3% 15-40 10.3% 14-40 9.8% 15-40 9.0% 14-40 9.6% Teacher rating Normal 0-11 78.9% 0-7 80.5% 0-10 78.1% 0-6 81.4% 0-9 81.3% 0-6 82.5%
Borderline 12-16 11.6% 8-11 10.2% 11-14 10.8% 7-9 9.6% 10-12 8.9% 7-9 7.8% Clinical 17-40 9.5% 12-40 9.3% 15-40 11.1% 10-40 9.0% 13-40 9.8% 10-40 9.7%
Note SDQ, strengths and difficulties questionnaire There were no significant differences in proportion by age band between parent and teacher ratings for either
Trang 6negatively correlated with externalizing behaviors (conduct
problems, hyperactivity/inattention: parent ρ = 0.32, 0.31;
teacher ρ = 0.50, 56, respectively) but showed little
correl-ation with internalizing behaviors (emotional symptoms:
were in line with the theoretical predictions, and com-mon in boys and girls All correlations were statistically significant atp < 0.01
Table 4 Results of exploratory factor analysis (Varimax Rotation) of parent- and teacher-rated SDQs for Japanese children
SDQ items Parent ratings (n = 24,519) Teacher ratings (n = 7,977)
Factor I
Factor II
Factor III
Factor IV
Factor V
Communality Factor
I
Factor II
Factor III
Factor IV
Factor V Communality Pro Hyper Emotion Conduct Peer Pro Hyper Emotion Conduct Peer
Initial eigenvalue 4.88 2.60 1.70 1.21 1.12 11.52 7.07 2.60 1.82 1.24 1.08 13.80
% of variance 9.06 16.82 23.68 28.39 33.03 16.68 28.53 38.89 47.25 55.22
Prosocial behavior
Hyperactivity/
inattention
Emotional
symptoms
3 somatic
complaints
Conduct problems
Peer problems
19 picked on,
bullied
23 best with
adults
Note SDQ, strengths and difficulties questionnaire *indicates a reverse item and inverted scores were analyzed.
Trang 7Internal consistency
Table 6 shows that internal consistencies were generally
good, with those of teacher ratings tending to be
stron-ger than those of parent ratings The relatively weak
in-ternal consistencies of conduct problems and peer
problems might be explained by the cross-loadings of
items 7 and 11 mentioned above Cronbach’s α
coeffi-cients were very similar for boys and girls
Inter-rater reliability
In a smaller subsample, parent-teacher correlations were
found to be moderate for total difficulties scores (n = 63,
44 boys, 19 girls, mean age 9.0 ± 1.3 years, 42 with
clin-ical diagnoses, 21 with no diagnoses; ρ = 0.40)
Spear-man’s rank correlation coefficients varied by subscale:
emotional symptomsρ = 0.49, conduct problems ρ = 0.33,
hyperactivity/inattention ρ = 0.34, peer problems ρ = 0.50,
and prosocial behavior ρ = 0.28 All were statistically
sig-nificant (p < 0.01 for all scales except for prosocial
behav-ior,p < 0.05 for prosocial behavior)
Test-retest reliability Thirty-four parents of a subsample (17 boys, 17 girls, mean age 10.4 ± 2.7 years, 19 with clinical diagnoses, 15 with no diagnoses) and 18 classroom teachers of chil-dren from community schools (12 boys, 6 girls, mean age 10.3 ± 2.8 years, 4 with clinical diagnoses, 14 with no diagnoses) completed the SDQ on two occasions (inter-vals: mean 54 ± 43 days, [14–137 days], mean 25 ± 25 days [10–107 days] for parents and teachers, respect-ively) Test-retest correlations of both parent and teacher ratings were excellent for total difficulties and all sub-scales (total difficulties ρ = 0.79, 0.95; emotional symp-toms ρ = 0.80, 0.76; conduct problems ρ = 0.76, 0.88; hyperactivity/inattention ρ = 0.70, 0.84; peer problems
ρ = 0.74, 0.79; prosocial behavior ρ = 0.87, 0.72; parent and teacher, respectively; all p < 0.01) Both parent and teacher ratings on two occasions did not significantly differ for any of the subscales except teacher-rated peer problems (Z = −2.14, p < 0.05, two-tailed test), indicat-ing overall temporal stability
Table 5 Cross-scale correlations for parent- and teacher-rated SDQs of Japanese children aged 7–15 years
(Spearman’s rho)
Parent rating (n = 24,519) Teacher rating (n = 7,977)
problems
Hyperactivity/
inattention
Peer problems
Prosocial behavior
Conduct problems
Hyperactivity/
inattention
Peer problems
Prosocial behavior
Note SDQ, strengths and difficulties questionnaire Parent ratings: boys (n = 12,472), girls (n = 12,047) Teacher ratings: boys (n = 4,010), girls (n = 3,967).
*p < 0.01.
Table 6 Cronbach’s alpha coefficients for SDQ scores of Japanese children aged 7–15 years
Note SDQ, strengths and difficulties questionnaire.
Trang 8Convergent and divergent validity
Table 7 shows the correlations between parent-rated
SDQ and CBCL/4-18 scores for 46 clinical patients
(36 boys, 10 girls, mean age 8.0 ± 0.8 years) and those
between teacher-rated SDQ and TRF scores for 29 clinical
patients (23 boys, 6 girls, mean age 7.9 ± 0.7 years) SDQ
total difficulties scores were strongly correlated with
CBCL total scores for ratings by both parents and teachers
(parent ρ = 0.56, teacher ρ = 0.77) Correlations between
corresponding subscales of the SDQ and the CBCL were
also moderate to strong: those between SDQ conduct
problems scores and externalizing scores of the
CBCL4-18/TRF (externalizing, delinquent behavior, aggressive
behavior subscales) were strong (parent ρ = 0.50-0.66,
emotional symptoms scores and internalizing scores of
the CBCL4-18/TRF (internalizing, withdrawal
prob-lems, somatic complaints, anxiety/depressed subscales)
were moderate to strong (parent ρ = 0.40-0.52, teacher
ρ = 0.50-0.57) All correlations were statistically
signifi-cant (p < 0.01) By contrast, there were no signifisignifi-cant
correlations among subscales measuring conceptually
different behaviors, as shown in Table 7
Similarly, Table 8 shows that SDQ
hyperactivity/in-attention subscale scores were strongly correlated with
the ADHD-RS total scores as well as the inattention and
hyperactivity/compulsion subscale scores for parent
rat-ings (n = 41 from local schools, 25 boys, mean age 8.1 ±
1.5 years) and teacher ratings (n = 43 from local schools,
27 boys, mean age 8.1 ± 1.5 years) Strong correlations
were also found between SDQ conduct problems
sub-scale scores and ADHD-RS total and two subsub-scales
scores By contrast, no significant correlation existed
be-tween the teacher-rated emotional symptoms subscale
score and ADHD-RS score, although the correlation was
moderate for the parent ratings
Discussion
Our results provided normative data of parent and
teacher SDQs for Japanese schoolchildren aged 7 to 15
years, and confirmed its reliability and validity
Gender and age effects in the general population
As for gender effects, both parents and teachers reported
higher levels of difficulties for boys than for girls, except
for emotional symptoms Such gender differences in
SDQ scores are well in line with previous SDQ studies
across ages and countries [13,15-19,21-24] and in the
original U.K study [35] In our study, observed gender
differences were more pronounced in teacher ratings
than parent ratings, a tendency that has also been
re-ported in previous studies using SDQ [13,16,23,35,36] A
possible explanation for this tendency is that girls might
be more able to adjust their behaviors to social situations
than boys Thus, we should exercise caution when inter-preting information from parents and teachers when assessing clinical severity Our finding of gender differ-ences emphasizes the need to establish a culturally cali-brated gender-specific norm for each SDQ rater version
As for age effects, both parents and teachers reported the highest levels of difficulties for the youngest chil-dren, aged 7–9 years, although we found no systematic differences for either peer problems or prosocial behav-iors In our study, we found a robust line of descending tendency with age only for parent ratings; the effect size for teacher ratings was negligible Many studies have re-ported a similar descending tendency of parent ratings with age [13,18,23,24,36], although no such age effect was found in community samples in Holland [19] or Hong Kong [16] or in an epidemiological sample in the United Kingdom [37] By contrast, except for a study from Shanghai, China [13], almost all studies, including ours, found no systematic age difference for teacher rat-ings [16,23,36,38] A Dutch study that examined par-ent, teacher, and self-ratings of the SDQ reported no age effect except in parent ratings [23] Although ADHD prevalence decreases with development [39], a recent prospective and longitudinal study revealed that childhood-onset psychiatric disorders are relatively stable, and homotypic or heterotypic continuity is found for each disorder, especially behavioral disorders such as ADHD [37] In other words, the descending tendency of parent ratings might reflect a phenotypic transition in their child rather than a true change in severity Instead, as children get older, they might begin to conceal worries and problems from their par-ents Therefore, researchers and clinicians might want
to consider the clinical significance of gender and age differences when applying normative bandings to spe-cific child populations [12]
Mean and cut-off scores of the Japanese version of the SDQ were lower than those for Europe, the United States, and China, although they were similar to those for Israel and Holland These studies cannot be easily compared because the age ranges studied in their samples were not identical However, the tendency for Japanese parents or teachers to give lower scores to children’s be-haviors appears consistent among questionnaires such as the CBCL [29], ADHD-RS [33,34], and Social Responsive-ness Scale [40,41] One partial explanation for the rela-tively lower scores of Japanese children on behavioral measures such as the SDQ is that Japanese informants tend to respond to Likert-type ratings by choosing the scale’s midpoint, whereas U.S informants tend to choose the scale’s extreme values [42] In fact, if the original U.K cut-off were applied to Japanese children, some Japanese children in the “clinical” range instead would be labeled
“borderline”, and some labeled “borderline” would fall into
Trang 9Table 7 Correlations between the SDQ and CBCL for each rater (Spearman’s rho)
problems
Somatic complaints
Anxiety/
dep
Social problems
Thought problems
Attention problems
Delinquent behaviors
Aggressive behavior
Internalizing Externalizing Total SDQ
Note SDQ, strengths and difficulties questionnaire CBCL, child behavioral checklist The subsample from which parent ratings were obtained (n = 46) consisted of clinical patients (36 boys, mean age 8.0 ± 0.8) The
subsample from which teacher ratings were obtained (n = 29) consisted of clinical patients (23 boys, mean age 7.9 ± 0.7) *p < 0.05, **p < 0.01.
Trang 10the“normal” range Thus, for both culturally appropriate
use and cross-cultural research, we must establish national
norms based on population distribution
Factor analysis
We confirmed the proposed five-factor structure for the
Japanese version of the parent and teacher SDQs using
EFA and CFA
Reliability and validity
Internal consistency, inter-rater reliability, and test-retest
reliability of the Japanese version of the parent and
teacher SDQs were generally satisfactory and
compar-able to the original version [14], and on the whole fell
well within previously reported ranges [43] On all
sub-scales of internal consistency, teacher ratings were more
reliable, a tendency that is in line with those of previous
studies [43] The test-retest interval of 10 days to 5
months in our study was wider than that in conventional
measurement, but the test-retest reliability from our
sample is comparable to that of samples with shorter
intervals of 2 weeks to 2 months [13,16,19] Therefore,
the true test-retest reliability with a shorter interval
might be even higher than the finding in the present
study [14,15]
Regarding convergent validity, strong correlations
be-tween the SDQ and CBCL support that, overall, the
Japanese SDQ measures the same construct that the
Japanese CBCL measures, as shown in many studies
[43] Again, the correlation was higher for teacher
rat-ings than for parent ratrat-ings At the subscale level,
cor-relations between SDQ behavioral difficulties subscales
(e.g., conduct problems and hyperactivity/inattention
subscales) and corresponding CBCL subscales were
higher than the correlation between the SDQ emotional
symptoms subscale and the corresponding CBCL
sub-scale for both parent and teacher ratings In addition,
the SDQ hyperactivity/inattention subscale was highly
correlated with the ADHD-RS measures for both parent
and teacher ratings This parent-teacher discrepancy or
externalizing-internalizing discrepancy appears to be con-sistent with the studies reviewed by Stone [43]
Limitations This study has a number of limitations First, despite a sufficiently large-sized normative sample, the validation sample was small and the clinical information was based
on experts’ clinical judgment obtained without a vali-dated structured interview in some cases Thus, we could establish neither discriminant validity nor calcu-lated sensitivity or specificity against psychiatric diagno-ses Second, the parent SDQ response rate was low (29.4%), although that of the teacher SDQ was accept-able (78.8%) Van Widenfelt et al [23] pointed out that children of responding parents but not non-responding schools are likely to show higher scores Also, we did not obtain demographic information (e.g., parental education level, income, and age; one- or two-parent family; number of siblings; teachers’ age and gen-der) that might be related to SDQ scores [12] Therefore, the representativeness of our normative sample for par-ent ratings is unclear, although the normative sample rated by teachers was representative Also, the influence
of demographic factors on parents’ or teachers’ ratings is unclear Third, because the age range of participants in the present study was restricted to school age (7–15 years), the applicability of the Japanese version of the SDQ for preschoolers is unknown Fourth, we did not study the self-report version for adolescents aged ap-proximately 11 to 16 years, who are an important target for community mental health service planning Thus, a future study examining its usefulness as a screening tool must include detailed clinical data from a larger clinical sample and investigate its ability to discriminate between community and clinical samples and receiver operating characteristic curves In addition, Japanese norms and psychometric properties of parent and teacher ratings for preschoolers and self-report for adolescents should
be examined
Table 8 Correlations between the SDQ and ADHD-RS for each rater (Spearman’s rho)
SDQ Inattention Hyperactivity/impulsivity Total Inattention Hyperactivity/impulsivity Total
Note SDQ, strengths and difficulties questionnaire ADHD-RS: ADHD-Rating Scale-IV The subsample from which parent ratings were obtained (n = 41) consisted
of primary schoolchildren (25 boys, mean age 8.1 ± 1.5) The subsample from which teacher ratings were obtained (n = 43) consisted of primary schoolchildren (27 boys, mean age 8.1 ± 1.5) *p < 0.05, **p < 0.01.